We have been using a TAKAGI TK20D tankless w/h for the past 7 years and we have had absolutely no problem with it. We use propane, have 2 full bathrooms, 4people (2 small chidren).
You'll find out that there are lot of options out there. One thing to consider is the debit. Chances are, they will try to sell you the top model with a 12 gallons per minute etc... Remember that the output of your tankless w/h is only as great as its input.... So if you get 6 gallons per minute at your house you won't get more that 6gpm at the water heater...
Ours is rated at 6.7gpm (IIRC) and we never had any output issues. You can run 1 shower, the dishwasher, the laundry machine and 1 faucet at the same time. I even installed a hot water garden line to use when I wash the car, the dog as well as fill up the hot tub...
I would recommend the electronic ignition, no need to pay for a pilot light and I think it is safer.
Good luck
Edit: I guess they don't make the TKD 20 anymore.... It has been replaced by the TH2.
http://www.takagi.com/index.php?product_id=85&page_id=2