I use the titanium heaters, they are all metal tubes with remote thermostats. So far quite reliable, many on here use them. I had a glass one and broke it, and from opinions here I got the titanium and am glad I did. They are comparatively priced and widely available. I hope this helps!! Others should input on reliability etc, everyone has thier own opinions and experiences, this is mine...There is also thinking as to adding 2 heaters that equal the size of one that you would use (2 150watt vs 1 300watt) as to add redundancy and possibly more efficient heating depending on placement....DO a search and you should fine lots of info on this...
Bill