The uke is my primary instrument. I played with the guitar years ago but gave it up when children arrived. I love my ukes and I have one of each size except the concert. I even have a banjo uke. You may want to attend a uke club meeting if there's one in your area. People at my club usually bring more than one so you'd probably be able to check out various sizes. They're tuned the same except the baritone. The baritone is tuned like the first 4 string of a guitar. Baritones really don't sound like ukes, they sound like small guitars, IMHO.
I pretty much agree with Guitarpix's comments. I'd suggest spending as much as you feel you could afford up to about $200 US. You can get good ukes for about $140 and adequate ukes for about $60. Cheap ukes are like cheap anything else, discouraging.
Funny thing. It seems the folks in their 40's and 50's are more generally critical of the uke. Older folks and younger adults seem to embrace them more readily.