Simply rhymes with:
accompli, amply, lampley, rampley, sampley, stampley, accompli, amply, bapley, capley, cheaply, chipley, copley, coupley, crisply, cropley, deeply, epley, eppley, harpley, kepley, lampley, leapley, lepley, panoply, principally, rampley, rapley, reapply, ripley, rupley, sampley, shapely, shapley, sharpley, sharply, shepley, shipley, stampley, stapley, steeply, supplee, tapley, tarpley, teply, whelpley
Simply sounds like:
sample, sampley, sanville, schnabel, schnebly, seasonable, semple, shamble, shambley, shameful, simple, sinful, sinopoli, snabel, snapple, snavely, sniffily, sniffle, snively, snowball, snowfall, snowmobile, snowplow, sunnyvale, symbol