Unless you have really wack proportions, balance between the wheels won't be a consideration. Seat tube angle is not a consideration in any case because the position of the saddle can be set as needed by adjustment in height of the seat post and fore/aft adjustment on the saddle rails or with a seatpost with the desired setback. That is a major part of the rationale behind the stack and reach concept as far as comparing frame sizes. Head tube angles vary only slight between bikes and a 1/2 degree difference will only make a mm difference in the fore/aft postion of the bars. Let's say the HT angle differ by 1/2 degree and the bars are 10 cm higher than the top of the head tube. The difference in bar position will only be 0.9 mm.