My vote is for the titanium heaters! More service reliability and they won't shatter like glass ones have the potential for. You may need to tweek the thermostat a bit, but so far my titanium heaters have all worked flawlessly. I've had the oldest one for about 2 years maybe and the other ones for about a year.
I'm editing this post to mention that two of the heaters are in the sump and hooked to my Medusa controller thereby eliminating the need to fiddle around with the thermostat. Turn it all the way up and let the Medusa decide when heat is called for or not. The Medusa has a pretty darn good thermostat...better than the ones on the heaters (actually, I have the chiller connected to it too).
If you do a search on this BB on the topic, you'll find many many opinions about all the available heaters. It would be a good idea to read through them to get a better picture of the overall advantages and disadvantages of the various heater choices.