I am an avid slug shooter and depending on price there are only three I would buy, but that's just me..

I'd look at the Bushnell Trophy in 1.75-4 power
Leupold VX-I 2-7 shotgun scope
Zeiss makes a really nice one with fixed eye relief

I have used the trophy and really liked it but right now I have the Leupold on three different slug guns and really like it.. I like the heavy cross hair and it has a very long eye relief but yet has decent field of view...