I Love bot mode Its fun to vs the bots and just crush them or to try out a new setup of guns and equipment or just use weird and wacky guns all and all very fun mode/feature added to the call of duty franchise.
but if it could only be in one call of duty game I would have to say MW3 the large number of interesting kill streaks would be endless fun and I feel there are more weapons in MW3 over black ops 1,2. I know they have the bot survival thing what is also fun but it's not like combat training At all.
Ive always liked combat training from BO1. Still had the grind of leveling up and buying new guns.
That was enjoyable but it's so hard to buy everything in the armory cause you have to buy the lens and sight stuff and camos every time for each gun. But I liked to BO1concept of buying your gear rather than be handed It for grinding though the levels.
CoD 2. I love sniping in that game, and I'd like to test my aim on some bots.