I've read that the Apex are junk with maybe the exception of the 502 model.
My 'perception' is that Magnavox and Venturer are el cheapo.
I would pick the Zinwell out of that list; is in the better pic and tuner category of CECBs and only of a few with timers (VCR); crummy EPG though and has been found to be glitchy on the timer and favorites programming (see thread, there may be workarounds to these problems).
The Artec makes a good Zenith/Insignia substitute that can still be bought online. Same chipset, quality, power miser, etc. Better EPG and can be run off of 12 V (automotive, etc.).
Check out the TRT thread, there are two boxes but I forget which one was prefered. This mysterious brand 'appears' to be the holy grail of CECBs but most of us didn't even know about it until it was too late (coupons expired) due to poor marketing by the company. They have to be bought directly from the company to the best of my memory (info in the thread). One box reminded me of a ChannelMaster (pic Q/tuner/s-video) with a great EPG AND a program timer, plus some other goodies.
I love my ChannelMaster though, my Zinwells make good VCR helpers, and my Artecs are good for camping (+ decent EPG).
Check out the aforementioned vote thread but I wouldn't put too much emphasis on the actual tally of votes. The reason being is that there is a very uneven distribution of votes (brick&mortar vs online, popular brands vs less known, etc.). Read through the folks' discussions though - good stuff.
Also watch your local Craigslist - I use the keywords "tv converter" in the category 'all for sale/wanted.' Note: Many folks are now selling TVs cheap and throwing in a converter that is worth more than the TV as they replace them with flat panels, so check out some of those ads within this search too.
You will have a remote control problem with any two of the same in close proximity but hopefully they'll be in different rooms. Some different brands will even control each other (ex: a CM will effect a Zinwell but not the other way around).
What's the diffierence between an OTA and portable antenna?