I prefer custom enclosures. Mostly for size and access, but also I want something that look like furniture because they are in my living room. I've not seen a front opening tank that's big enough for my liking, and I am really short so its a hassle to reach into a top opening tank. It's nice to have the solid walls to attach things too and not have to cover up as much window. I also prefer a solid top - heat is trapped better without so much screen and let's my enclosure serve as a table/stand.
The draw backs I've experienced:
Unless you get a pvc enclosure, wood/melamine is heavy. My wood enclosures take two people to move and weigh a lot (75-100lb+)
Glass is expensive and acrylic scratches easier.
A solid top limits options for height, so adjusting basking lights and uvb isn't as easy as a screen top.