Best is very subjective. Sig Sauer and H&K are among the best in general.
Look for a book by Dieter Marschall
It is a cheap German-made revolver of uncertain quality.
German made; 50-100 USD or so
Open
Glock
Best is a relative term that has to many variables.
Inexpensive; 20-50 usd
20-50 USD. German made, not very well as a rule.
Best left to a qualifed gunsmith
Whichever one best suits your needs.
Best left to a gunsmith
200-450 or so