I challenge you to find and post a single reputable reference that does not show San Diego to have historically produced outstanding returns for a modest length hold.  

Reputable contractors will likely have some sort of social media presence where you can parse through some of their previous projects and work. 

Here's a PARTIAL list:Office rentComputers, printers & softwareInternet & phone billOffice furnitureOffice supplies: paper, postage, ink, etc.Office liability insuranceAuto expenses: monthly payment, insurance, gas, maintenance, registration/plate feesBroker license fees: annual, monthly board & MLS fees, continuing education fees, E&O insuranceEquipment: lockboxes, signs, etc.Business income tax preparation and paymentsStaff payroll & payroll taxes Time Tasks: answering phones, calling past due tenants, scheduling tours, taking marketing pics, processing those pics, writing ads, researching rent amounts, posting ads, explaining to owners how rent determined & showing where ad posted, opening & processing mail, posting payments, bank deposits, scanning documents & posting to owner & tenant portals, explaining accounting to owners so they understand their monthly statements, taking pics/videos of repairs, finding reputable handymen and contractors, confirming they're properly licensed & insured and tracking annually, verifying repairs done properly, processing invoices for utility bills, repairs, taxes, city inspections, scheduling periodic property evaluations/inspections with tenants that don't want strangers in their homes, explaining to owners why taking so long, and more & more & more...

On the flip side, agents may steer clear of companies with bad communication, payment issues, subpar services, unappealing commission rates, or bad reputations.

Is the title company reputable - this part is easy2.

Steady deals that perform well and a solid reputation in the industry.  

Valuation for Property Management 3X to 5X Seller Discretionary Earnings or 1X to 1.5X Annual Revenue, depending on how well established the brand and reputation is in the market, market share, number of units, scalability, etc...Transaction Structure, never buy a Property Management business for cash,  you must include an earn-out structure or provision to protect the purchase against clients/property owners leaving post-transaction.  

There are some very notable exceptions, and I'll send you a few deal syndicators from around the country that are reputable and 1031-friendly via PM. 

I agree with Min's suggestion to start with a reputable turnkey operator. 

Protecting one's digital reputation is important.