Bear-Wrestling: Improved Unarmed Strike, Improved Grapple & Stunning Fist
Mounted Combat: Ride-By Attack, Spirited Charge & Trample
Piscator: Exotic Weapon Proficiency (net), Improved Trip & Improved Critical
Strong-Arm: Power Attack, Improved Sunder, Great Cleave
Throwing: Quick Draw, Point Blank Shot, Far Shot
Out of those, Strong-Arm is the obvious choice, as you'll only ever get the first feat anyways so the rest don't really matter.
Note tho, Able Learner doesn't work quite like you think. Basically, normally you have some class skills and cross-class skills. Your class skills have maximum cap of 3+Your Character Level (this applies if a skill is a class skill for any of your classes so taking a level of Ranger = all Ranger-skills forever have the maximum cap rank of 3+Your Character Level for this character) and cross-class skills have maximum cap of ½ that, rounded down.
Further, however, cross-class skills cost twice as much to take. That is, it costs you two skill points to take 1 rank of a cross-class skill. This is not mitigated even if the skill is a class-skill for your other classes, so if your Ranger 2/Barbarian 1 wants to place a 6th rank (5 ranks as Ranger) to Hide when taking the level of Barbarian, he pays 2 skill points for it. This is where Able Learner comes in; it makes all skills cost you 1 skill point/rank no matter whether they're class skills or cross class skills.
However, there's this little detail that Able Learner is Human-only feat. You can probably ask your DM to remove that restriction tho.
EDIT: It occurs to me my explanation of Able Learner was convoluted. An effort to make it more clear:
Class Skill: Cap rank 3+Character Level. Every rank costs 1 skill point.
Normal Cross-Class Skill: Cap rank (3+Character Level)/2. Every rank costs 2 skill points.
Cross-Class Skill that is a class skill for another class this character has:
Cap rank (3+Character Level)/2.Cap rank 3+Character level. Every rank costs 2 skill points.
Cross-Class Skill on a character who has Able Learner: Cap rank (3+Character Level)/2.
Every rank costs 2 skill points.Every rank costs 1 skill point.