I think I know which way I'm going with this, but I need a soundboard, so please bear with me...

Currently all I have for water purification is a couple of Sawyer hollow membrane filters. I'm looking at getting something more robust for the house for a SHTF/bug-in scenario.

Option one is a Katadyn Ceradyn. The pros here are that it'll filter 39,000 gallons, is fairly easy to maintain, and the filters will never expire. Cons are that it won't filter out chemicals or heavy metals, it's relatively slow, and it's not easily portable. The slowness is somewhat offset by being able to fill the top/dirty portion and let it filter while you do other stuff.

Option two is the Grayl Geopress. Pros are relatively quick filtering, no real maintenance required, it filters chemicals and heavy metals, and it's extremely portable. Cons are that the filters are only good for 10 years in their packaging/3 years once used/65 gallons of water per filter, and that they will only filter 24 ounces of water at a go. If I go this route, I'll be buying 2-3 of the kits plus a bunch of extra filter cartridges.

What would you do?

I can't speak to the two you're looking at but the Big Berkey filters have a lot of fans so that might be worth adding to your list.  It looks to be in about the same class as the stuff you’re looking at.  Do your own due diligence on this as they don’t test their stuff to the same standard as everyone else.  What’s your water source, how much are you looking to produce and for how long?

My system is pre-filtering with sand, running it through a Sawyer Point one, Sawyer Point Zero 2 and then through activated carbon and bone char in a homemade filter.  I’ll be tapping the creek behind my house here in suburbia.  The system is scalable from nothing to something north of 100 gallons a day and I’m hoping to get a couple of years out of it.  Anyway, that’s the plan and it remains a work in progress.

I've got the Berkey and like it a lot.  Always watch when they say some huge number of gallons filtered, that depends on a lot of things in the water.  Even not bad stuff like calcium can clog up a filter pretty quick.  Know your water source and test it for six months to see what it does to your filter(s) then go from there.

Ive used a ceradyn for several years.
I run 2 vs 3 filters in it. Its plenty fast. Ive only cleaned them twice, ( its used daily).

I live in Florida and did some research and found that a lot of Florida's canal and Everglades water sources are contaminated with runoff pesticides and phosphates from farming fertilizer. The hollow fiber filters like the Sawyer would not remove any chemicals. In the past, the General Ecology First Needs XLE was my portable filter of choice as lab results posted show a significant chemical and pesticide reduction. The Big Berkey with black filter elements was my choice for home and long term. Berkey posts lab tests results showing greater than 99 percent reduction in many chemicals as well as bacteria. There are a number of other ceramic type drip filters similar to the Berkey that may work well also. I just could not find ceramic elements that matched the lab test results of chemical reduction by the Berkey Black elements. The Berkey is still my choice for long term and ease of use. My buddy bought the Greyl on a camping trip recently. The Greyl seemed to produce clear water from slightly tannin water, but after a few quarts, took significant effort to press the water though the filter. It seemed the filter was getting clogged after a 4 or 5 quarts. It continued to work, but was just difficult to press the water though. Unlike some other filters, you cannot clean the filters. Some of the Youtube review and Amazon reviews also show some clogging issues. I also considered the Greyl as a portable, but could not find lab test results showing chemical reduction percentages. If you end up with the Greyl, get plenty of spare cartridges. In a SHTF scenario, you will need to filter lots of water for possibly an extended time. The Berkey is easily serviceable by gently scrubbing the elements with a scouring pad. Buy a spare spigot and washer kit and buy several packs of scouring pads. The First Need XLE is still my choice for portable purifier with capability of chemical removal. As always, have backups.

Florida Everglades water test results https://pubs.usgs.gov/circ/circ1207/major_findings.htm

I have various water filters made by sawyer including the low micon models for virus. My backup is an 18 acre lake from two springs and some surface run off. During grid down there is no telling how hygienic my neighbors will be so a virus level filtration is important to me.

A few years ago our local power company had ash pits fail causing contamination. We are down stream from this but it has yet been detected in the ground in my area. We ended up purchasing a big berkey (6gallon) with 6 filters and the fluoride filters. Our community well is treated. After 6 months we find that we fill it every other day. It is used exclusively for cooking and drinking and we are a house of 7. We considered under the sink filtration but the gravity only design makes up for the hassel. Once primed at setup it just works. Also knowing it's always there and working and not one more thing I need to setup when the Chuck Schumer hits the fan.

If it is a bug in situation, i would get some rain barrels like the Bushman 265 (or a pair of them) and then go with the Katadyn Ceradyn. The Katadyn should be overkill for rain water.

I have a bushman 265 and a 130. Plus two 55 food grade drums in the basement. It rains frequently where I live, so being able to collect rain water solves a lot of problems. Plus, it is fairly clean and doesn’t require a lot of filtration. I can use pool shock in the rain barrels from time to time and then just pour it in the countertop filter.

With my two bushmans, the pair of 55s and the hot water tank, i usually have around 550 gallons of water on hand that doesnt require fancy filtration.

I do have a Katadyn Expedition and some Sawyers just in case.