Evony

  Evony is well known to just about any person who plays browser RTS games. Evony would be the best RTS game out there if there weren't so many people using real money to be better than everyone else. If you like fair games, this isn't the game for you. I quit Evony because you just can't survive without paying to compete with the other paying players.
  Evony has a great selection of buildings and each one can be upgraded. Buildings can be built with food, lumber, stone, or iron (the four resources used in Evony, other than money). Buildings include barracks, cottages, embassy, etc. Players can get multiple cities by getting certain medals. There is also a wide variety of troops you can train. Each troop has a certain amount of food it consumes daily and resources it needs to be built. Wall defenses can also be built.
  Heroes lead your troops into battle.Their level and skill affects the troops under their command. You have choices of what you want to do with your troops. They can attack, plunder, or colonize. You can also take over other players' cities.
  The Fortune Wheel in Evony gives you a random prize. Sometimes it gives you extra units and sometimes you can get with a useless item. Here is another factor in the unfairness of Evony. Some people get stuck with all the pointless prizes while some hit the jackpot. The Fortune-Wheel is a major factor when starting off the game.
  Overall Evony is a great game. It gives you plenty of options to control your cities and makes you feel like a king while you play. If you are new to the game though do not be surprised  if you loose everything after a month or so of playing. People who pay start farming everyone around them to feed their massive armies.
  I would recommend this game to anyone who wants an addictive RTS game. http://www.evony.com/

Afterwind

  Afterwind is a turn-based game that can keep you addicted for months. The game involves the entire world. The place in the world where the match is played is determined by the host. There are many options the host can play with such as turn length, maximum number of players, location where the game is played, etc. This game can be played in a quick match,which can last hours, or can played in long term matches where the turn-length goes by days.
  Afterwind involves troops and money. The money buys you troops and the troops help defend/attack. The more land you take, the more money you make, which leads to more troops. Alliances can be made and war can be waged. After you win/lose a match you get a certain number of points based on your performance during the game. These points add up over time and can earn you upgrades for certain troops or to buy new strategies.Strategies are used based on how you play the game. Some strategies allow you to have better offensive than defense, and others the exact opposite.
  In this game you can't build buildings, only units. This is a game devoted to war. Your economy is how much money you are making a turn. There is no morale in this game either. This game is all about how strategic you are with your troops and what alliances and enemies you make.
  Overall this game is a masterpiece. This game can keep you entertained for hours at a time (if you play the quick match version). I would recommend this game to anyone.

Supremacy 1914

 Supremacy 1914 is possibly the best browser RTS game i have played yet. Set in the time period of WW1, this game gives you a nation to control. With almost every nation in close proximity of each other, this game can get very tense and very fun. Instead of joining a world where everyone is located, this game is played in matches. Each match can last a very long time, I believe up to 2 months. You can have as many matches (games) going as you want. Having about 10 games going can keep you occupied for the next month or two.  You can also buy (goldmark) for this game. Goldmark allows you to give your troops or cities extra morale, buy military units, rescources, etc. You start off with 10k goldmark.

  Every nation starts off with 100 troops. Each troop stands for 1,000 troops. The objective of the game is simple, take as many other nations down as you can, and reach the score limit. Each nation starts off with a set of provinces too. Each province has morale, just like your troops, which can determine the production of the material that province produces. Each province has a city where you can store troops and make buildings such as forts, workshops, barracks, harbors, etc. Each building has upgrades except for your capital and harbor. Workshops upgrade to factories which can give you artillery, railguns, battleships, etc. Nothing feels better than taking a load of artillery and completely destroying your enemies' armies.

  I have not seen a better WW1 RTS game than this. All the options you have to run your empire is amazing. The feeling of being the superpower of the world, or just taking over another nation makes the game worthwhile. I would recommend this to ANYONE who likes strategy games.