Some folks check the “max render quality” box in circumstances where it doesn’t help, but only increases render time. If all your footage is the same rez, it doesn’t do much.
In your case though, with multiple resolutions, it may help. Your renders will take longer.
Depending on your deliverable codec, if it offers a two-pass mode instead of one-pass, two-pass mode will help. Two-pass renders will increase your render times.
And of course, the higher the bitrate, the more data is kept instead of tossed. Higher bitrate will mean bigger finished files.
Without more info about your original footage resolution, wrapper, and codecs, these are the basics I can suggest.
System:
Dell Precision T7600 (x2)
Win 7 64-bit
32GB RAM
Adobe CC 2017.1 (as of 8/2017)
256GB SSD system drive
4 internal media drives RAID 5
Typically cutting short form from UHD MP4, HD MP4, and HD P2 MXF.