That's a wide open question but I'll assume you are referring to a
benchtop chisle mortiser. The General gets good reviews and the higher
end Delta too. I've worked with the low end Delta and I hate it. The
action is stiff and the adjustments are crude, it flexes too much, the
stops on the fence suck, the fence itself sucks, the depth stop sucked
until it just completly broke.
I would opt for a tilting head model. If you go for the General the 1"
version has a better table and can handle the bigger chisle vs the 5/8"
Of course you could be a millionaire and just want one of the Italian
beauties that you just pass the stick in one end it it comes out the
other end all milled up. If you go for one of those models get the
integrated espresso machine too. ;^)