IMHO- Centerpoint, followed by Carbon Express
I've owned, shot, broken, and repaired two Carbon Express CX series crossbows. I successfully killed deer with both over several years, but one x-bow cracked the limbs when the string jumped the nock on the bolt. May have been my fault in seating the bolt, I don't know. The repair shop had to file the limbs down to get them to fully seated in the limb pockets, all four limbs had rubbed and squeaked loudly when cocked from new.
The other CX sheared some of the hardware on the barrel, nothing hard to replace or expensive, but annoying.
They were both accurate to 50 yards, and I really can't complain too much about either one, I use mine regularly through out the summer practice season, and through the early/late seasons.
Several of the budget minded hunters in our deer management group have Centerpoints, and have been happy with the x-bows, one I'm thinking of is on it's fourth season, and gets used regularly.
I've switched over to Excalibers Micros, but TN is right, a good used Excaliber would be a good starter - only complaint I have with the older models is that they tend to be pretty loud - louder than many current x-bows.
An elderly family friend borrowed my Micro and killed a bull elk in Idaho three weeks ago, full pass through at 40 yards. Bull never flinched until the bolt hit him - died with 30-40 yards of the hit, using the Excliber "Bolt Cutters" BH.
