The cheap ones off Aliexpress have fairly inaccurate crystals - they're 100 ppm or more off, which you can compensate for to a certain extent but that's another step. By comparison, the rtl-sdr.com one looks particularly spiffy: http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/
In my experience they're 30-70 ppm off, never seen one over 100, but it's extremely easy to adjust and all apps pretty much support it, most tutorials tell you right off the bat how to do it. Once you've got them configured they're surprisingly pretty solid.
The rtl-sdr.com dongles there say 1-2 PPM, but that's only 1-2 PPM temperature drift, right? The one I linked also uses the R820T2 tuner, which does seem to be somewhat more accurate. You're still going to have to mess around to get the right offset at first. Just less messing around for the first 5-10 minutes while it heats up.
Honestly, if it's something you're really interested in and want to put some money into I'd buy a HackRF instead, $300-400 but you'll be able to dump way more spectrum and transmit.
I unfortunately don't have one of the rtl-sdr.com dongles (wish I did) but the spec says there's a 2 PPM initial error plus 1 PPM temperature drift, which is fairly reasonable for a cheap TCXO. My current dongle is a cheap one from AliExpress with slightly over 100 PPM of offset, and finding a calibration procedure that actually worked was... interesting.
How solid they are depends on the environment they're in. They primarily vary by temperature so if you're using them in an air conditioned room they're unlikely to have issues but if you leave them outside you'll notice the PPM value varying throughout the day.
