Note there are two types of right angle finders. One is simply RA (Right Angle) and the other RACI (Right Angle Corrected Image).
The RA one will reverse the image left right as does a star diagonal in a refractor or SCT, neither of which then match a star chart or unaided view.
An RACI or straight through finder does not reverse the image left right. In a straight through the image is upside down but it still matches a star chart. Being upside down is not normally a problem as often you look from the side and can twist your head or spin your star chart to match.
If you are using a Newtonian reflector get a straight through or RACI finder. If low to the ground an RACI makes it easier otherwise a straight through if on a larger EQ mount higher off the ground.
Stellarvue make 1.25" finders in straight or RACI configuration and you can either use their 23mm cross hair eyepiece which can be illuminated or supply your own standard eyepiece. See
http://www.stellarvue.com/finderscopes.html
I personally prefer a non-illuminated non cross hair eyepiece and even Stellarvue recommend a highly corrected eyepiece given the f3.75 focal ratio of their finders. The use of a highly corrected eyepiece has only one disadvantage and that is cost but the main advantage is sharper stars to the edge of field and when you are looking for faint fuzzies, sharp stars to the edge also means a galaxy is likely to be seen at the edge than be invisible due to distortion from a poor eyepiece.
I use a Meade 20mm Plossl in my Stellarvue F80M finder but occasionally use a 16mm T5 Nagler for simply spectacular views. The latter gives me almost 19x and over 4 deg. field which nicely matches the outer ring of a Telrad.