I think that both ways are interesting and they bring a lot of benefits to power system. I recommend you to see not only technical solutions. you must  observe the economic advantages.

Both are good,but in my opinion FACTs may be better oppertunity.Because with helping in transmission,they are maintaining good p.f also(e.g-UPFC,TSC etc).Loss is less.Maybe with the point of view of ecomony,reliability,maintenance those factor may deside whichever is the best option in case to case.

As per my opinion using FACTS will be a good solution from the point of economy and reliable operation and may also depend on the circumstances where it is employed.

Both system have their own advantages. And use of Facts device is important in both system for reactive power control and voltage regulation. HVDC transmission gives the controlled and fast power injection during any deficiency of power. And as the scenario is changing, most of the distributed power plants will be in the category of DC generation in which there can be direct DC transmission using HVDC. Also it is to be noted that HVDC converters itself need reactive power to work and HVDC interacts with AC system better when we make AC system's strength upto a suitable level by using Facts devices. Therefore, we can decide which one is better after analyzing the system where it is employed.

AS we know that for economical point of view, HVDC transmission is done only when transmission distance is more than 500 or 600 kms as the cost of the converters at both of the sides of HVDC transmission is very high. So if the distance of transmission is less than 500 kms, it is preferable to use EHVAC wiith FACTS devices.

HVDC is best option for Transmission purposes. But due to the constraint of Economy and also old system existing presently necessitates for FACTS devices in order to have better control and performance which is economical than full switching to HVDC transmission.

we all discuss about the benefits of FACTs devices but what are the disadvantage of FACTs devices?

The disadvantages of FACTS were:

1) Expertise required in the Technical Field.

2) Rating of Switches is a constraint.

3) Complexity increases with the Better Control options.

4) Topology varies as per the requirements which is also quite complex.

5) Once the Fault occurs on the FACTS installed line, it is not possible for the FACTS device to isolate from the line within the minimum Power cycle to which the Power electronic Switches can withstand.

Both are complementary technologies:

The role of HVDC is to interconnect ac systems where a reliable ac interconnectionwould be too expensive :-Independent frequency and control. -Lower line cost . -Power control, voltage control and stability control possible

 The large market potential for FACTS is within AC system on a value added basis where : -The existing steady-state phase angle between bus node is reasonable. -The cost of FACTS solution is lower than the HVDC cost . -The required FACTS controller capacity is lesser than the transmission rating

in my work i use FACTS devices to support reactive power compensation for the HVDC converter stations ....which need reactive power about 50-60% of the rated active power during it is operation.