If I moved to England, I'd buy Pheidologeton so fast. Land, move into place, buy. No second thoughts. They replaced Leafcutters as my #1 favorite ant species. That species is amazing, tiny workers and huge majors/soldiers with huge colonies. The best ant species in the world to me.
In U.S, I like Pheidole megacephala the most. Not native in California, but super easy to keep. Except I had to freeze a couple of mine because they just got wayyyy too many and got mites somehow. Plus population issues. Even though I freeze all food and even freeze the dirt before putting them in. However, I still have a colony of them and they are doing great. They don't escape, eat a large variety of food and have supercolonies. Huge bonus, they don't sting like Argentine ants or Solenopsis invicta do. Argentine ants always give my mom an allergic reaction, but she had Ph. megacephala crawl on her from when gardeners brought them in on plants and no reaction at all. Only problem is I need to freeze a portion of them as they just grow and grow and grow.
For native ants, I prefer keeping...well...Pheidole...they get soldiers. They eat seeds. Always active and very hardy in captivity. However, I've never had a captive Pheidole colony (of the native kind) and only kept workers of them. Never once found a native Pheidole queen.
I also like Forelius pruinosus/mccooki. They have tons of queens in each colony, produce tons of brood in captivity, eat everything, extremely hardy (only ant out on pavement in 120 degree weather). Super easy to keep.
I also like Pogonomyrmex and Veromessor species.
Mostly though, I prefer ant species that start with Pheid...funny that... And other seed eating ants.