Sorry if I've misunderstood it, but you're asking what one, overall, is best used for:
1) Staying in a state of REM sleep once sleep is induced
2) An anxiolytic drug to calm you down when used pro re nata - do you suffer from panic attacks/anxiety or something, as well as insomnia? If so I'd recommend using something such as Diazepam instead of Temazepam/Triazolam for this need, as it's a better anxiolytic as opposed to hypnotic. You can/should use the Diazepam for anxiety in conjunction for the Temazepam/Triazolam for insomnia. They're similar but have remarkable differences in terms of their effects profile and shouldn't just use one or the other as a 'catch all' drug.
3) Abuse of such medication for 'feeling good'
As your focusing is on staying asleep as opposed to inducing sleep, I'd stick with Temazepam as it's widely considered to be the Benzodiazepine that has least affect on your REM stages of sleep, meaning a better quality of sleep throughout the night. I don't know as much bout Triazolam but similar to Temazepam also I think it does affect the REM stages less than other common Benzos such as Alprazolam (Xanax) / Diazepam (Valium) / Clonazepam (Klonopin) / Lorazepam (Ativan) so it could still be an option.
Firstly, if Temazepam is currently working fairly well for you - why are you looking to change it?
Secondly (and if you're not being prescribed Temazepam/Triazolam and it's thus a choice of obtaining one or the other illegitimately - then that's a different matter) but you seem to have been given the option of changing to Triazolam from Temazepam, are you not able to swap and trial it? This is under the assumption that such offer of change has been proposed by your GP/Physician? Could you not try Triazolam and then if it's no better, go back to Temazepam.
Lastly, if you genuinely suffer from insomnia and rely on Benzodiazepines then I wouldn't use/abuse them to feel good as your tolerance is only going to shoot above the ceiling.
Also, have you considered trying the Z-Drugs: Zolpidem & Zopiclone?
