Best of 3 TAB price always? Not quite so regarding Sportsbet. The devil is always in the rules detail:

167. 'City Best Plus' and ‘City Best’ applies to all metropolitan race meetings in Sydney, Melbourne, Brisbane, Adelaide and Perth.
167.1 City Best Plus is available for Win only and Each Way ('EW') wagers when placing wagers online and at least matches the best Win dividend declared by two of the national TAB's, UNiTAB and the Starting Price (refer to rule 173.).
167.2 The Place portion of EW wagers will be paid at the better dividend of one quarter win SP dividend or the best of the three national TAB's.
167.3 If less than 10 runners, the Place portion of the EW wagers is paid at City Best (refer to rule 167.5).


Having pointed that out, I'm not saying Sportsbet is a poor betting choice but there are advantages to a TAB, like easy cash in cash out and access to exotics etc.