As rsn48 states , in N there is no one best track choice. It all depends on what features are important to you.
Kato Unitrack - good points - easy to work with - great choice of crossings, radii and turnouts, great for temporary set ups and test tracks, extremely durable. down sides - expensive and unrealistic toylike look.
Atlas Code 80 - had been the standard in N for a long time, plus sides - N trak acceptance, no flange interference problems, great availability and relatively inexpensive. Downsides - appearence.
Atlas code 55 - plusses - great appearence - finescale look to ties and rails, good availability and relatively inexpensive. downside, flange intereference with older MT cars and locomotives, even some newer locos reported with interference, necessitating expensive and time consuming low pro wheel changeouts and risky loco flange turndowns. current selection of crossings and turnouts limited. to be fair the track meets NMRA recommended practices and most older wheels don't.
Peco Code 80 - see Atlas code 80 above - very similar, slightly more pricy, their turnouts have been the standard in N for a long time due to positive "snap action". downside - "european" look - (not a downside if modelling european outline

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Peco code 55 - basically Peco 80 set further into the ties to give a fine scale rail look. Does not interfere with older flanges on all but the most outrageous pizza cutter wheels like Arnold used to have. Good availability and selection, but still has european look. In my opinion FWIW - this is currently the best track choice in N, durable, available - easy to work with, great quality. Hopefully Peco will reconsider a US proto track.
Micro Engineering Code 55 and 70 - great looking track - probaly the best looking N track there is. Availability spotty, and fragile - recommended for experienced modellers for the most part - the 70 seems to be the right compromise in rail size for less interference problems and fine look. ME code 55 has less problems with wheel interference than Atlas 55, but is more expensive and harder to find than Atlas.
Keep in mind there is no real US proto track or ties standard - rail weights vary from main to branch, tie width and spacing vary from road to road etc.