Primarily if you think well of them or if you know them to be inferior. The only ones I yet know are Strategy Desk from TD Ameritrade and something called Trade Station. Thank you. References to other threads are fine so you needn't repeat already typed material.
Kind of a huge subject - there are many different autotrading platforms out there ranging from retail-friendly software options like Tradstation, Ninjatrader, Multicharts, and Metatrader to online services like zulutrade (terrible rep as far as I know) , collective2, tradency, to brokers like Oanda or Thinkorswim or Interactive Brokers that allow trading via an API. I wouldn't necessarily recommend any of them. Many who are serious about autotrading write their own software and trade via a brokerage API. There are also higher-end services for larger investors and funds that can cost up to 5 or 6 figures per month in fees. Sounds like you're just getting started in your research. There are so many choices its impossible to list them all but if you post more about what you're looking to do exactly and how much money you have to spend and what products you're looking to trade you might get some more precise answers. Also wouldn't hurt to do some searching on past threads here on ET as this subject is discussed fairly often.
GoldStandard, thank you very much. I am checking TradeStation from the firm of the same name. Do you know any others to be better? I would like to profit from small gains or losses in stocks as they fluctuate within a trading range I anticipate, using market orders. In other words, simple but effective formulas.
I'm not reccommending either one but if you like Tradestation you might want to compare it to Multicharts,which is mostly compatible with Tradestation easylanguage and somewhat cheaper, and doesn't require you to use Tradestation brokerage or buy data from Tradestation.
sierracharts for retail traders, there's only 1 sierracharts learn to use it, it's $18 a month, it will do it all and blazing c++ speed fast.
MC starts at $99/mo and can be cheaper if you commit longer term and pay in advance. TS is $99/mo but can be free if you do a reasonable amount of trading and generate offsetting commissions. TS is also free if you open a Forex account (recent development). TS does a nice job of bundling the data so you don't have to go hunting all over for it. This is particularly so with historical data. With Forex data, it's free. MC has some nice portfolio testing features that TS doesn't have (yet).
I use Metatrader platform to develop automated trading systems of my strategies to trade the FOREX markets. You can check out one of my systems' performances here: https://www.myfxbook.com/portfolio/ton-amie/149973