Which is the best and most reliable exchange to trade BTC for XRP (Ripple)?

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There are 4 English exchanges listed for buying Ripple:

http://www.xrpga.org/exchangers.html

https://xrptrader.com : English : XRP, BTC
https://justcoin.com : English, Spanish, Norwegian : XRP, BTC, LTC, NOK
https://technocashier.com/ : English, Russian : XRP, WMZ, EUR, RUB, BTC
http://www.ripplewise.com/ : English : XRP, BTC, USD

But xrptrader.com is offline which worries me.  Is there a particularly reliable one in the bunch?