Any basic SSL will be fine for most uses, including storing personal data or financial information. There are other certificates that require additional validation such as business validation or extended validation.
While it's debatable whether or not these more expensive SSL certificates can provide any more security than the cheaper ones, it definitely boost some customers confidence knowing that your business/entity is a registered name. While the cheaper certificates only validate domains.
If you plan on using the SSL on cPanel/WHM based hosting a dedicated IP is not required due to the SNI feature.
Most end-users would be wary of submitting any personal information via a non-secured connection. Considering the cost of an SSL certificate, if you are considering collecting any sort of personal information at all, it is generally worth it.
As for shared vs dedicated, shared SSL certificates generally reside on a domain other than your own, and don't look quite as "professional".
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