big bore,
I'm assuming you have a Contender. Are you considering other action types or just the Contender?
From factory offerings in the Contender the 7x30 Waters would be my top choice for a good goat gun.
As far as what I have used on antelope, 7mm TCU, 7mm-08, 284 Win. I have taken more antelope with my 284 Win than the other two combined. i haven't hunted antelope much in the recent past, but if I were to today I would be using my 6-284, 6.5-284 or if I really wanted to stretch things my 7mm Dakota (All of these are in XP-100's though).
The 6-284 & 6.5-284 would work well in the Encore if you have one. The reason I would personally consider the 7 Dakota for myself is for it's wind defeating ability at the longer ranges. It just outperforms everything I have, hands down in terms of the lack of horizontal drift.
The 30-30 case necked down & improved in 6mm, 25, and or 6.5 would also make great antelope choices.