Looking to buy a VHF/UHF mobile antenna.   Not looking to spend a lot.   Will live on roof of Tacoma.

Concerned about ripping it off when off-roading so I want to go mag mount.   Any suggestions?

8nBAIT

The Comet SBB series provides the best RF performance, but they are not the most rugged.

The best magmount would be a 5" diameter base.

Even that does not provide a lot of ground plane.
A hood mount would have more ground plane than the large mag mount base.

I have a Tacoma.  I drilled the roof and purchased a Larsen NMO dual band 1/4 wave .  It has a spring base that works pretty good bending when low hanging limbs come across the roof. I use this truck in the woods adding plenty of pin striping in the last nine years.   Not the best preforming antenna but it stays in place and is low enough for most parking garages.

This sort of a fender bracket works well, is easy to install, and will leave no trace when eventually removed if you mount it under the hood as I do. I always use one existing bolt, then add a small sheet metal screw just so it can't twist. You can get these at Amazon or HRO just for starters. I usually reshape it to better match the contours of the body so that it will mount low and tight.

Cheers...   Jim

IMG_3354 by Jim QRB, on Flickr

https://www.amazon.com/Valley-Enterprises-Antenna-Chevrolet-2014-2018/dp/B07HB92HPK/ref=sr_1_18?ie=UTF8&qid=1542818328&sr=8-18&keywords=nmo+mount+bracket

this YMMV

nope

a mag mount antenna is capacitive coupled to the car body...... which is a wonderful ground plane

Yup

I have an NMO 1/4w VHF antenna on my roof that has great performance, durability not so much. I have to pull it going into garages and such.

I've been kicking around the idea of moving to a tool box mount or fender mount using an NMO bracket like in the picture above.

I bought a shiny new Ford F-150 last year, and was going to take a 100 plus mile trek to go to a hamfest. I had not yet mounted a radio in it, so I took an HT, and thought to use a tiny mag mount antenna I have to improve the performance of the HT.

I put the antenna base near the body expecting to hear the "thunk" of the magnet latching on. Nope. Hmm, maybe over here? Nope. I knew the Ford had some aluminum body components, but hadn't realized it was ENTRIRELY aluminum. Boy, did I feel dumb! I guess I need to go back to HRO and buy the aluminum magnet version of this antenna.

I really like the Laird C144/440Cs
https://www.theantennafarm.com/catalog/laird-technologies-c144-440cs-6596

The Larson NMO2/70b is nice as well
https://www.theantennafarm.com/catalog/larsen-nmo2-70b-1712

You should put forth the money into a Sti-Co Flexiwhip. Can tie the thing into a knot and it'll untie…I actually just sold a towing company a bunch of them because the contractor that installed their radios did roof mounts when they company wanted fender mounts due to low clearances. They were constantly folding over 1/4 wave UHF whips when performing repos in parking garages. Haven't had an issue with the Sti-Co.

OP, antennas for off roading are an interesting balance. With 1/4 wave antennas, you can get away with mag mount setup but you can still throw them if you are not careful (throwing them does a number to your paint, just an FYI). Also over time, mag mount antennas can cause some other forms of paint damage which you can eliminate going with NMO roof mount antennas as long as you keep the weight and moment of the antenna in mind. For the most part, I've settled on a handful of commercial antenna combos for my needs. Also to note though he recently upgraded to a Sierra, @TLF has a Taco which he radio'd out of for awhile and can show his installs and maybe talk about the time he pulled a seat just so I could align one of his radios (which is a pet peeve of mine for single radio installs, not multi-like his).

Anyway, my favorite combos are as follows. Panorama Sharkee with Tri-band whip. I run one on my pickup in combination with a Motorola Tri-plexer but I keep an eye on the whip still. On my last DD, I ran a Sti-Co Flexi for VHF and a PCTEL 430-480 MHz knob for UHF after I ripped a Comet CA-2x4SR out of the roof due to a tree branch strike. On my Jeep, I run a Larsen NMO-Q with spring for VHF on the roof and a Larsen NMO27B on the fender for CB. Park in a garage and don't have any issues with it. My company rig is an interesting one though. Bear in mind, my company rig is a retired ambulance and as such has a minimum clearance of 8'6". On that I run a Motorola branded (Laird Antenna Specialists) VHF 1/4 wave antenna with spring, 7/800 MHz knob and Antenna Specialist UHF Transit antenna. Almost anything I drive under gets strikes the VHF whip and I have no issues.

I agree with everything Zap said above. I'm a HUGE fan on the PCTEL knob style antennas. Low profile and truly impressive performance. I'll put it this way, I used to keep a collinear UHF antenna in my truck in the case that I needed extra performance. I never used it. No issues working repeaters 50+ miles away. (Using a Motorola XTL)

OP, for what you are wanting to do individual monoband, through the roof NMO mounts, are the way to go. It'll blow anything else out of the water.

My usual suggestion is a Sti-Co Flexi-Whip. Just cut it for 2m and it'll work ok for local 70cm repeaters. Could always just switch it back and forth to a higher performance antenna as needed.