Silver classic 350 with some custom black stickers on it. i feel silver and black make a good combination. now talking about the most popular colors, when RE classic 350 was launched initially it had only 2 variants, that was black and the silver and you can see lot of them on roads which makes black and silver most popular colors in 350cc category. Royal Enfield later came up with various color and at present it have the following colors in 350cc category.
If you plan to buy 500cc then desert storm will be a good option. presently they have the following colors in the classic RE 500cc category.