Same question many of us have asked ourselves through the years. Do people "know you" by your present call sign?
Do you have thousands of QSL cards already printed with your present callsign?
An amateur's callsign use to tell what geographic part of the country the amateur operated in, about the time they were first licensed and what "class" they were (novice, tech/general/adv , or extra). This has changed over the past 10 years.
The choice of a callsign (with the 1986 FCC vanity program) now centers on different criteria:
a.) Do you wish the number designation (0-9) to correctly identify the part of country (QTH) in or were first licensed in (former QTH)? [Not required by FCC for continental US, but still useful]
b.) Prefix (W, K, N, A) Personal preferences tend to follow the order shown, unless you are in a US territory or AK, HI.
c.) Suffix. Name initials, hobby or work interests (SSB, CW, FON, DX, ISS, SPC, APR, IP, etc.). Easy of sending/receiving during DX contests or CW.
d.) x by x Do you desire a 1 by 2, 1 by 3, 2 by 1 or 2 by 2 callsign. Usually in that order.
These are the usual "first round" considerations, when looking at the available vanity calls.
ex-WB9MKT (1975 - 1996) Tech,General,Advancd,Extra
ex-WN9MKT (1973 - 1975) Novice
I actually miss my old "MKT", that is why W9MKT was my second choice back in 1996 when the vanity program started.