If you are wanting a .308 Winny then the Contender is automatically out of the race. That round is too high pressure for the Contender...but if you want something with the .308" bore diameter then you can get the .30 Herrett, 30-30 Win, 30-30AI or .309 JDJ in the Contender which would be great.
Back to the .308 Winny cartridge ...I personally love the Striker...as a rested gun. They are way to large to effectively shoot offhand. For antelope there is a great chance you will have a good rest to shoot from...a backpack, rock, shooting sticks, etc. I don't really care for the plastic stock though...too cheapo for my taste. The wood stock Super Strikers are nice though. Used Strikers (w/ the plastic stock) can be had for around $300. Do you get Handgun Hunter Magazine?? There is an article in it about making the Striker adaptable and switching barrels very easily. I've heard the author of that piece REALLY knows his stuff!
Then the Encore...it will also do the job very well and you probably already know the pros on it...easy to change barrels, barrels are everyhwere for sale, and a very quality handgun. The con is the price...they are expensive to buy a complete gun.
Best thing to do.......find someone who has each and shoot the guns.