Any 30-30, .243, .270 or .308 makes for a great deer round (yes I left off the '30-06 , I think its overkill). As for a favorite, it depends. The .243 is awesome for recoil shy shooters, but can be marginal for northern bucks. This isn't to say it won't work, as in fact I've never seen a 243 fail to kill a deer, but when considering the BEST round for deer, it can be a little light. The .270 rules ranges over 200, although it's velocities up close can cause some meat damage when using lighter 130 gr. bullets. The .308 gives low velocities so it will not cause as much meat damage within 100 yrds, but can drop quite a bit when considering shots over 200. Personally, I choose to use 150 gr. 270 bullets out of my Remington 700 BDL for deer, but when it comes to the BEST deer cartridge, any one of the four above are gold. Just know where to shoot.