Unfortunately benzo's only work for anxiety for a reasonably short period and inevitably make the condition worse.
Awesome for short term use, the occasional comedown etc though.
Out of the three you list I personally find diazepam to be the best anxiolytic. I also like 30mg Temazepam as a weekly guaranteed decent sleep to take the edge of the insomniac grind.
For harm reduction purposes please take great care with the benzo/alcohol mix, that combination has led to a lot of fatalities. Also, be prepared for a special kind of hell should you develop a benzo adiction - try and keep a couple of days minimum between consumption.
Maybe have a look at some non-chemical anxiety reduction techniques - meditation especially is an awesome tool.
EDIT - hardly anyone finds benzo's euphoric, only in as much as they relieve the anxiety (for a while....)